What issue? The "smoothness" of the curve should be corrected by the precision parametzer as suggested above, and the issue with the curve going above or below the actual data points cant be solved. If you interpolation a spline between data points, and the y values of the data points are not monotonously increasing or decreasing but go through some kind of minimum or maximum, then the interpolation curve may gop easily above or below the data points.

paradoxoff wrote:What issue? The "smoothness" of the curve should be corrected by the precision parametzer as suggested above, and the issue with the curve going above or below the actual data points cant be solved. If you interpolation a spline between data points, and the y values of the data points are not monotonously increasing or decreasing but go through some kind of minimum or maximum, then the interpolation curve may gop easily above or below the data points.